Starter for internal-combustion engines.



H. MIDGLEY.

STARTER FOR INTERNAL COMBUSTION ENGINES.

A PPucAT|oN FILED FEB. 20, 1915,

Patented Apr. 22, 191$).

, UNITED STATES PATENT OFFICE.

ALBERT HENRY MIDGLEY, OF ACTON VALE, ENGLAND, ASSIGNOR 0F ONE-HALF TO CHARLES ANTHONY VAN DERVELL, OEACTON VALE, ENGLAND.

Specification of Letters Patent.

Patented Apr. 22, 1919.

Application filed February 20, 1915. Serial No. 9,717.

. of which the following is a specification.

This invention relates to an improved electric starter for internal combustlon eng nes such as 1s used for the driving of motor cars and other purposes and of the kind in' which an electric motor is used in combination with a helical gear which has a longitudinally displaceable member and is interposed between the electric motor and the en-' gine to be started in order to effect and maintain the coupling during the starting operation and automatically to effect the uncoupling.

In starters of this kind, as hitherto proposed, in addition to the means forstarting the electric motor, separate means have been employed for effecting the engagement or.

the initial engagement of the driving gear.

The present invention consists in effecting the initial engagement of the driving gear by a short longitudinal movement of the shaft of the electric motor, which longitudinal movement is produced by energizing the magnetic field of the motor and then automatically completing the said engagement by the sliding movement of one member of a helical gear on said shaft, the automatic disengagement being effected by the same means operating in a reverse direction. In the starter constructed according to the present invention, the shaft to which the armature of the electric motor is secured has a small longitudinal movement relatively to the axis of the magnetic field, which movement is just sufiicient for bringing the teeth of the members to be coupled together into initial engagement with one another.

It is known to effect the coupling between the gear members of an electric starter for internal combustion engines by securing one of the gear members to a shaft to which is attached a motor armature arranged to be drawn into the magnetic field by the magnetic action of the latter. However, in this form of starter as hitherto constructed the whole of the coupling is effected by the longitudinal movement of the armature relatively to the axis of the field, which movement must necessarily be comparatively long as it has to cover the distance between the gear members when they are out of engagement with each other and the full width of the movable gear member. The electric starter constructed according to the present invention has the advantage as compared with this form of starter that the longitudinal movement of the armature is reduced to the small distance between the gear members when they are out of engagement with each other and consequently the energy required for the excitation of the motor at the beginning of the starting operation is also reduced and the size of the motor is decreased.

The invention is illustrated by way of example in the accompanying drawing.

Referring to the drawing, the armature Shaft a of an electric motor 12 carries a pinion 0 which is rovided with spiral teeth and which is slic ably mounted on the shaft a, the latter being for this purpose castellated as shown at d or provided with a key. The electric motor 5 is preferably of the type in which when the motor'receives the current from the battery the armature, together with the shaft a and the spiral pinion a mounted thereon, are moved longitudinally because of the attraction between the armature and the field magnet, thereby bringing the spiral teeth of the pinion c in engagement with the spiral teeth provided on the other member 6 of the gear, the latter member being preferably formed on the flywheel f of the engine. Immediately upon the initial engagement of the two members 0 and e of the spiral gear, the spiral pinion a on the armature shaft a is caused to slide on the latter because of the rotation of the armature, whereby the two members 0 and c are caused to come into full engagement with each other. The engine having thus been started the tendency thereof to drive the motor 6 causes the spiral gears c and e to come out of engagement with each other, in which position they are kept by means of a spring 9 interposed between the pinion c and a member k taking up the axial thrust and adapted to rotate on a ball bearing 2'.

The connections of the electric motor with the battery may be as follows :The armature n and the excitation windings 9 provided on the poles of the electric motor 6 ,are connected with a split battery 1 ,1

operative; by shifting the arms to the posi tions in which they make contact with the stationary contacts m and a, respectively,

the excitation windings g are connected across'the largerportion Z, of the battery and at the same time the armature p is con- 7 nected to the smaller portion Z, of the battery, the circuit being; battery Z arm n, contact 7b,, a resistance 0, brush 70 commutator j, armature p,commutator j,jbrush 70 stationary contact m arm m, and back to the battery Z When the arms are in this position a large current is sent through the excitation windings q and a small current is sent through the armature p whereby the ar mature p is strongly attracted within the magnetic field under slow rotation, By further shifting the arms into such positions that m is disconnected from m, and 02 makes contact with the stationary contact w the armature p is connected in series with the excitation windings Q and with the whole of the battery Z Z theJcircuit being battery Z 1,, arm a, contact 7%,, brush 10 commutatorj armature p, commutator j, brush 70 excitation windings g, and back to the battery. Whenthe circuit is thus completed, the speed of rctationof the armature is increaseduntil' the engine is started. Having now' described my invention, what I claim as new and desire to secure by Letters Patent is g V 7 1. An'electric, starter for internal com,- bustion engines for automatically effecting the coupling of the engine and starting H10: tor, comprising in combination with the engine shaft an electric motor "having a longitudinally displaceable armature shaft, a helical gear having two cooperating mem- Gopies of this patent may be obtained. for

bers, one of which constitutes a driving member and is mounted on the longitudiously rotating the armature shaft and longitudinally displacing it, together with the said driving member mounted thereon, to a position of initial coupling between the two shafts through the intermediary of the driving member, whereby the further rotation of the armature shaft, after the said initial coupling, causes the one member of the helical gear to shift longitudinally relatively to the other member thereof, thereby completing the coupling between the two shafts, as set forth.

2. An electric starter for internal combustion engines for automatically effecting the coupling of the engine and starting mo-. tor, comprising. in combination with the engine shaft an electric motor having a longitudinally displaceable armature shaft, keyways provided on a portion on the armature shaft, and a pinion slidingly mounted on the said keywayed portion and provided, 7

with helical teeth, a wheel mounted on the engine shaft and provided with helical teeth which are cut to correspond to those on the said pinion so as toconstitute together a helical gear, andmeans for simultaneously rotating the armature shaft and longitudinallydisplacing it, together with the pinion mounted thereon, to a position of initial coupling between the said pinion and wheel, as and-for the purpose set forth.

. In testimony whereof :I have signed my name to this specification in the presence of 7 two subscribing witnesses.

we Witnessesi 7 J. HETTINGER,

F, N. PAGE.

five cents each, by addressing the Commissionerof Patents, -Washingt0n, D. C.

ALBERT HENRY MIDGLEY. 

